DTD parsing, CLI, and BaseModel support

[Nicholas-Schaub]

Excellent library. I was able to successfully generate a a tool for parsing fairly complex XML. There were a few bumps in the road, so I thought I'd give some feedback and see if there are some things you might find useful.

For reference, the library I generated:
https://github.com/nicholas-schaub/pubmed-types

You can see the entire generation process and run it yourself if you're interested, since it uses a nox workflow. You can find it in noxfile.py, and can run it by installing with pip install nox and running from the commandline using nox.

First, dtd support wasn't documented, but I tried running it on a dtd file and to my surprised it worked. However, it wasn't able to properly link mml:math, and it's unclear to me where the issue with this is. I played around with the .mod files and the entity definitions, but I just could not get it to link properly. Fortunately, the other schema I was trying to convert had the same class, so I was able to go in and link to the Math class generated by the other schema. But I had to manually modify the file, as you will see in the noxfile workflow. So I guess my question/comment would be: Is this an issue with the dtd, or is this a quirk of the current implementation because dtd isn't officially supported?

Second, a minor comment: Could you add an input argument to the CLI to ignore a top level folder? A common practice in making Python libraries is to put all source code into a src folder. The reason for this is that this additional layer helps to prevent a local import while testing. However, when I try to generate pydantic classes I get an __init__.py in the src directory that I have to manually remove.

Third, could you support pydantic.BaseModel instead of just pydantic.dataclass? I ask because BaseModel has some useful serialization/deserialization functionality that the dataclass doesn't have. It's obviously still possible to get the same functionality, but it's more boilerplate work.

I realize this is a lot. I'm happy to close this issue and submit issues for each topic to make them more granular.

[tefra]

see #23 for pydantic v2, for the other issues please open tickets in the xsdata repo please